﻿// PendingBuffer.cs
//
// Copyright (C) 2001 Mike Krueger
// Copyright (C) 2004 John Reilly
//
// This file was translated from java, it was part of the GNU Classpath
// Copyright (C) 2001 Free Software Foundation, Inc.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
// 
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent
// modules, and to copy and distribute the resulting executable under
// terms of your choice, provided that you also meet, for each linked
// independent module, the terms and conditions of the license of that
// module.  An independent module is a module which is not derived from
// or based on this library.  If you modify this library, you may extend
// this exception to your version of the library, but you are not
// obligated to do so.  If you do not wish to do so, delete this
// exception statement from your version.

using Flowertwig.Utils.Compression.ZLibExtensions;

namespace Flowertwig.Utils.Compression.General
{

    /// <summary>
    /// This class is general purpose class for writing data to a buffer.
    /// 
    /// It allows you to write bits as well as bytes
    /// Based on DeflaterPending.java
    /// 
    /// author of the original java version : Jochen Hoenicke
    /// </summary>
    public class PendingBuffer
    {
        /// <summary>Internal work buffer
        /// </summary>
        protected byte[] buf;

        int start;
        int end;

        uint bits;
        int bitCount;

        /// <summary>
        /// construct instance using default buffer size of 4096
        /// </summary>
        public PendingBuffer()
            : this(4096)
        {

        }

        /// <summary>
        /// construct instance using specified buffer size
        /// </summary>
        /// <param name="bufsize">
        /// size to use for internal buffer
        /// </param>
        public PendingBuffer(int bufsize)
        {
            buf = new byte[bufsize];
        }

        /// <summary>
        /// Clear internal state/buffers
        /// </summary>
        public void Reset()
        {
            start = end = bitCount = 0;
        }

        /// <summary>
        /// write a byte to buffer
        /// </summary>
        /// <param name="b">
        /// value to write
        /// </param>
        public void WriteByte(int b)
        {
            if (DeflaterConstants.DEBUGGING && start != 0)
            {
                // throw new SharpZipBaseException();
            }
            buf[end++] = (byte)b;
        }

        /// <summary>
        /// Write a short value to buffer LSB first
        /// </summary>
        /// <param name="s">
        /// value to write
        /// </param>
        public void WriteShort(int s)
        {
            if (DeflaterConstants.DEBUGGING && start != 0)
            {
                // throw new SharpZipBaseException();
            }
            buf[end++] = (byte)s;
            buf[end++] = (byte)(s >> 8);
        }

        /// <summary>
        /// write an integer LSB first
        /// </summary>
        /// <param name="s">value to write</param>
        public void WriteInt(int s)
        {
            if (DeflaterConstants.DEBUGGING && start != 0)
            {
                // throw new SharpZipBaseException();
            }
            buf[end++] = (byte)s;
            buf[end++] = (byte)(s >> 8);
            buf[end++] = (byte)(s >> 16);
            buf[end++] = (byte)(s >> 24);
        }

        /// <summary>
        /// Write a block of data to buffer
        /// </summary>
        /// <param name="block">data to write</param>
        /// <param name="offset">offset of first byte to write</param>
        /// <param name="len">number of bytes to write</param>
        public void WriteBlock(byte[] block, int offset, int len)
        {
            if (DeflaterConstants.DEBUGGING && start != 0)
            {
                // throw new SharpZipBaseException();
            }
            System.Array.Copy(block, offset, buf, end, len);
            end += len;
        }

        /// <summary>
        /// The number of bits written to the buffer
        /// </summary>
        public int BitCount
        {
            get
            {
                return bitCount;
            }
        }

        /// <summary>
        /// Align internal buffer on a byte boundary
        /// </summary>
        public void AlignToByte()
        {
            if (DeflaterConstants.DEBUGGING && start != 0)
            {
                // throw new SharpZipBaseException();
            }
            if (bitCount > 0)
            {
                buf[end++] = (byte)bits;
                if (bitCount > 8)
                {
                    buf[end++] = (byte)(bits >> 8);
                }
            }
            bits = 0;
            bitCount = 0;
        }

        /// <summary>
        /// Write bits to internal buffer
        /// </summary>
        /// <param name="b">source of bits</param>
        /// <param name="count">number of bits to write</param>
        public void WriteBits(int b, int count)
        {
            if (DeflaterConstants.DEBUGGING && start != 0)
            {
                // throw new SharpZipBaseException();
            }
            //			if (DeflaterConstants.DEBUGGING) {
            //				//Console.WriteLine("writeBits("+b+","+count+")");
            //			}
            bits |= (uint)(b << bitCount);
            bitCount += count;
            if (bitCount >= 16)
            {
                buf[end++] = (byte)bits;
                buf[end++] = (byte)(bits >> 8);
                bits >>= 16;
                bitCount -= 16;
            }
        }

        /// <summary>
        /// Write a short value to internal buffer most significant byte first
        /// </summary>
        /// <param name="s">value to write</param>
        public void WriteShortMSB(int s)
        {
            if (DeflaterConstants.DEBUGGING && start != 0)
            {
                // throw new SharpZipBaseException();
            }
            buf[end++] = (byte)(s >> 8);
            buf[end++] = (byte)s;
        }

        /// <summary>
        /// Indicates if buffer has been flushed
        /// </summary>
        public bool IsFlushed
        {
            get
            {
                return end == 0;
            }
        }

        /// <summary>
        /// Flushes the pending buffer into the given output array.  If the
        /// output array is to small, only a partial flush is done.
        /// </summary>
        /// <param name="output">
        /// the output array;
        /// </param>
        /// <param name="offset">
        /// the offset into output array;
        /// </param>
        /// <param name="length">		
        /// length the maximum number of bytes to store;
        /// </param>
        /// <exception name="ArgumentOutOfRangeException">
        /// IndexOutOfBoundsException if offset or length are invalid.
        /// </exception>
        public int Flush(byte[] output, int offset, int length)
        {
            if (bitCount >= 8)
            {
                buf[end++] = (byte)bits;
                bits >>= 8;
                bitCount -= 8;
            }
            if (length > end - start)
            {
                length = end - start;
                System.Array.Copy(buf, start, output, offset, length);
                start = 0;
                end = 0;
            }
            else
            {
                System.Array.Copy(buf, start, output, offset, length);
                start += length;
            }
            return length;
        }

        /// <summary>
        /// Convert internal buffer to byte array.
        /// Buffer is empty on completion
        /// </summary>
        /// <returns>
        /// converted buffer contents contents
        /// </returns>
        public byte[] ToByteArray()
        {
            byte[] ret = new byte[end - start];
            System.Array.Copy(buf, start, ret, 0, ret.Length);
            start = 0;
            end = 0;
            return ret;
        }
    }
}